Statistics of intracellularly recorded end-plate potentials have been used to determine the applicability of the Poisson and the binomial distributions to the fixed and variable latency models of neurotransmitter release. Data was obtained from nerve-muscle preparations of cold-adapted mammals under normothermic and hypothermic conditions. Except when quantal content or release rate was very low, the binomial distribution provided the best description of data associated with either fixed or variable latency release. This finding enables determination of the parameters p and n for the data. The exact nature of p and n in physical or physiologic terms is unknown. Thus, an attempt is being made in this research project to determine the effects of neuromuscular blocking agents, centrol nervous system depressants and calcium ions on p and n in order to provide insight into their nature. In addition, the pharmacology and physiology of esophageal and cricopharyngeal striated muscles isolated from dogs and sheep are being investigated with regard to their alterations in achalasia.